Projecting-lamp.



G. A. H. KELLNER.

PROJEGTING LAMP.

APPLICATION FILED AUG. 2, 190'7.

Patented Se t. 13,1910.

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Q/vi in zoom G. A. H. KELLNER.

PROJECTING LAMP.

vAPPLICATION FILED AUG. 2, 1907.

Patented Sept. 13,1910.

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" PROJECTING LAMP.

APPLICATION FILED AUG. 2, 1907.

Patented Sept. 13, 1910.

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eus'mv, anemia: KELLNER, or nocims'rna, NEW YORK, assrenon, IBY MESNE vlissremmmus, '10 nausea & 1.0m; OPTICAL COMPANY, A coaromrrou or NEW YORK, (No. '2.)

PROJEGTING-LAMP.

To all whom it may concern:

Be it known that I, GUSTAV A. HERMANN KELLNER, of Rochester, in the county of Monroe and State of New York, have invented certain new and useful Im rovements in Projecting-Lamps; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of the specification, and to the reference-numerals marked thereon.

The present invention relates to projecting lamps of the type employingl a lens and a reflectorwith a source of lig t arranged between them in such a manner that two pencils of rays are formed, one, the reflected and refracted rays, producing a powerful illumination" at a great distance, and the other, the directly refracted rays, s reading illumination near the lam on y. A

been that,owing to the spherical aberration of the lens or the reflector, or both, the reflected rays do not issue from the lens as a homogeneous beam, or in other words, parallel to the optical axis of the lamp, and, as a consequence, a sutficiently powerful illumination at a distance is not secured.

This invention has for an object to provide a, lamp in which the lens and the reflector are so formed and so arranged relatively to the light source that the reflected rays issue from the lens parallel to the optical axis and thereby produce a condensed and powerful beam.

To these and other ends the invention consists in certain improvements and combinations of parts all as will be, hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings: Figure 1 is a lamp constructed in accordance with my invention, in which the reflector acts to correct the spherical aberration of the lens. Fig; 2 isa diagrammatic view of the optical elements of the same lamp. Fig. 3 is a view of the optical parts of a lamp in which a lens with spherical aberration corrects a reflector. Fig. 4 is a like view of lamp parts in which a reflector normally without spherical aber- Specification of Letters Patent. Patented Sept, 13,1910, Application filed August 2, 1907. Serial No.- 386,694.

ration corrects the lens. Fig. 5 is a like View in which both the lens and the reflector are without spherical aberration, and Fig. 6 is a like View in which a reflector without spherical aberration is combined with a lens without spherical aberration, arranged with its convex face disposed toward the reflecton,

In the present invention a beam of parallel rays isseoured-by having the axial and the marginal rays of the, lens focus at the focal polnt of the optical combination and by locating the source of light at this point.

This optical relation of the parts may be obtained in various ways, for instance, in the embodiment shown in Figs. 1 and 2 there is provided a condensing lens 1 spherically under-corrected that is, one which, if it is to project parallel rays, must receive its light from a focal point which is nearer to the lens as the ray approaches the margin of the latter; for example, in the lens shown the light 'must' emanate from the point A on the optical axis X to produce the marginal ray a, from the point B for the ray b, from the point C for the ray 0, from the point D for the ray d and so on, I combine with this lens 2 a spherically overcorrected reflector preferably in the form of a lens mirror, that is, a mirror having two faces site sign to that of the lens and preferably of like amount, so as to have a correcting eflect on the latter, or in other words, so as to focus the marginal, axial and other rays from the lens 1 at the point F or the focal point of the optical combination, or from still another point of view, to reflect images of a light source 3 arranged at the focal point F at distances from the optical axis X corresponding to thespherical aberration of the lens, and in this manner cause the lamp to project parallel rays. As an exam 1c of a construction made in accordance wit this form of my invention, I may combine with a lens, which is arran ed at 91.8 mm. from the focal point F and has a diameter of 220 mm., a radius of 187.2 mm. and a thickness of 42 mm., a lens reflector arranged 55 mm. from the focal point F and having an inner radius of 96 mm., an outer radius of 136.5

mm. and a thickness of 4 mm. at the optical.

axis.

- Instead of having the reflector exercise a correcting effect on the lens, the latter may be able to exercise a correcting eflect on the reflector as shown in Fig. 3. In this form I employ a spherical mirror or reflector 2 which, as is well known, is spherically under-corrected and combine therewith a lens 1, which is spherically over-corrected, in

cos. a

+ gging-z) tan. s

In this equation a=index of refraction r=radius of mirror=l m=distance of light source from mirror t: distance between plano face of lens and vertex of mirror lo -thickness of lens Z =co6rdinates of point on curve z=projection on optical axis of section of mirror between vertex and point where ray strikes, q =angle under which ray strikes plano face sflaangle of refraction in glass.

' The invention is also embodied in the construction shown in Fig. 4, wherein I employ an over-corrected condensing lens 1*, a hyperbolic reflector 2 and a light source 3. As is well known, if a light source be located at the geometrical focus of a hyperbolic reflector it will be imaged free from spherical aberration at the other geometrical focus of the hyperbola, but if the light source be located away from this point the rays will appear as if thrown by a reflector with spherical aberration. I utilize this latter fact in correcting the s herical aberration of the lens 1 and 'to t is end I mount the light source away from 'the focal point of the hyperbolic reflectorQP, so as to produce a spherical aberration of opposite sign to that of the lens. As an .example of a construction in accordance with this embodiment of my invention I employ a hyperbolic reflector in which the equatlon of its curve 1s The geometrical focus of this reflector will be 55 mm. from its center. The lens combined with the reflector should have a radius of 280.794 mm. and a thickness of 63 mm. and its plano face should be arranged 14:7 .512 mm. from the center of the deflector. If now the :light source be located on the optical axis at 64 mm. from the vertex of the reflector the latter will exercise a correcting effect on the lens, and rays substantially parallel to the optical axis of the lamp will be projected by reason of the axial and. the marginal rays of the lens focusing at the focal point of the combination. By this arrangement exactly parallel rays are not projected but the angles of the rays with relation to the optical axis are so small that a very condensed beam is produced. For instance, with the construction above described, a ray striking the reflector at an tangle of 40 'degrees, 8 to the o tical axis 1 issue from the lens at an ang e of 11.77 to the optical axis crossing the latter in advance of the lens, whereas rays strikin thereflector at angles of 52 41, 58 44 and 6 25, will issue from the lens at angles of 1.32; 6.76 and 1.84: respectively, to the ptical axis, crossing the latter in the rear of the lens.

My invention is further embodied in the construction shown in 'Fig. in which 1? indicates a reflector, such as a hyperbolic reflector which is free from spher1cal'aberra-.

v where I d +b +a=distance of image of flame a +b a.= distance of flame from vertex from vertex.

origin, is

l cos. g0

cos. c,

sin. sin. o,

where a is distance of focus from plano face, K is thickness of lens, a is index of refraction of lens, is the angle any ray at the focus makes with optical axis.

Instead of presenting the plano face ofthe lens to the source of light, as shown in Fig. 5, the curved face may be turned inwardly, as shown in Fig. 6. In this embodiment the convex face of the lens 2 is in the form of a hyperbola and the reflector 1 is a hyperbola, as in the embodiment shown in Fig. 5, the

light source 3 being at thefocal point of the reflector and of the combination.

In all embodiments of my invention the o tical parts may be supported in any suit-- a le manner, as for instance, by the casing 4 in Fig. 1. This casing may be provided with a shutter 5 movable to the position shown in dotted lines for the purpose of cutting off the reflected rays so that the lamp may be used only to disperse rays. The light source is preferably an acet lene gas burner,

' as this produces an intense i ht.

It will be noted from the oregoing that I have provided a lamp which Wlll project a very condensed beam and alsogive strong spreading rays adjacent thereto. These results make the lamp very desirable for use on 1 automobiles Wherenot only must illumination far ahead be secured, but the immediate path in front of the vehicle must be clearly visible. 7

I claim as my invention.

1. In a projecting lamp, the combination with a light source, of a lens and a reflector, having spherical aberration of opposite signs.

2. In a projecting lamp, the combination with a light source; of a lens and a reflector having spherical aberration of like amount, but of opposite signs, and arranged so that rays will be projected parallel to the optical axis of the lamp.

3. In a projecting lamp, the combination with a light source, of a condensing lens having spherical aberration and arranged to distribute rays received directly therefrom, and a lens reflect-or directing rays from the light source to the condensing lens and having spherical aberration of opposite sign to that of the condensing lens.

GUSTAV A. HERMANN KELLNER.

Witnesses:

HAROLD H. SIMMs, RUSSELL B. GRIFFITH. 

